The present invention relates to a bonded composite of a first thin-section element of sheet material and a second thin-section element. bonded together by bond elements defining a bond pattern. More particularly, one of the contemplated applications for the present invention is in bonding e.g. an outer cover and a body-side liner thin-section elements of absorbent articles to one another, as a bonded composite.
Absorbent articles are known as personal care hygiene products. Such absorbent articles find use, for example, as diapers, training pants, incontinence inlays, and women""s sanitary pads. Such absorbent articles can absorb and store liquid bodily excretions such as urine, menstrual fluid, or blood. Women""s sanitary pads are used, for example, to absorb the liquids excreted prior to, during and after menstruation.
In absorbent articles, the portions of the article where different layers or components are bonded to each other tend to incur significant stress concentrations, and in absorbent articles using conventional bond patterns, tend to fracture at such bonded locations under such stresses. In conventional patterns used in absorbent articles, bond locations are disposed in uniform and crossing straight lines and straight rows of circular bond elements. The inventors herein have noted that, when the absorbent article tears, the tear tends to propagate along the side edge of the bond pattern. Tearing properties of such conventional bond patterns can be compared to tearing of a paper form along a perforated line of weakness.
The problem for the present invention is thus to provide a bonded composite employing a bond pattern and an absorbent article implementing the bond pattern, whereby the position of adjacent bond locations is not linear, and whereby, the configuration of the bond pattern discourages fracture of the bonded composite or absorbent article.
It is an object of this invention to reduce the tendency of the bonded composite or absorbent article to tear, by employing bonding locations and configurations that prevent straight-line fracture and thereby spread a stressing force throughout the bonding pattern.
It is another object to configure the bonding locations such that a stressing force, when imposed on a respective bond element, is distributed into the interior portion of the bond pattern, forcing a potential fracture to propagate in a longer, and more-difficultly-propagated, non-straight path.
In a first family of embodiments, the invention comprises a bonded composite. The bonded composite has, as a first thin-section element, a first layer of thin-section sheet material, and a second thin-section element bonded to the first thin-section element by bonds defining a tear-resistant bond pattern. The tear-resistant bond pattern has a length, and a width represented by first and second side edges of the bond pattern. The bond pattern reflects application of pressure urging the first and second thin-section elements toward each other in face-to-face relationship to form an array of separate, distinct, and spaced interlocking arcuate bond elements affixing the first and second thin-section elements to each other in the process of fabricating the absorbent article. Each bond element has spaced first and second ends and corresponding end portions, and an arcuate intermediate portion between the first and second end portions. At least portions of the arcuate intermediate portions of selected ones of the bond elements are disposed toward respective side edges of the bond pattern. The ends of the respective bond elements are disposed inwardly of the side edges.
Substantial portions of the arcuate intermediate portions of selected ones of the bond elements are disposed toward respective side edges of the bond pattern.
The shape of the intermediate portion of a respective bond element can comprise a substantial portion of an ellipse, a substantial portion of a circle, or a substantial portion of an hyperbola.
The first end portion of a first bond element can intersect or cross a first imaginary line connecting the first and second ends of a second bond element, and the second end portion of the second bond element can intersect or cross a second imaginary line connecting the first and second ends of the first bond element.
The intermediate portions of respective ones of the bond elements can include inflections, and can extend from the first side of the bond pattern to the second side of the bond pattern.
The bond pattern may comprise an array of the bond elements arranged in a longitudinally-repeating pattern, such that respective ones of the bond elements are positioned at repeated width locations and at repeated longitudinal spacings along the length of the bond pattern.
The width of the bond pattern between the first and second side edges can be about 4 millimeters to about 14 millimeters, preferably about 5 millimeters to about 12 millimeters.
The arcuate bond elements can be activated by application of thermal energy, ultrasonic-frequency energy, and/or adhesives, to at least one of the first and second thin-section elements.
At least one of the first thin-section element and the second thin-section element can comprise a polymeric material selected from the group consisting of polyolefins, polyesters, and polyamides, and copolymers, mixtures, and blends of such polymeric materials.
At least one of the first thin-section element and the second thin-section element can comprise a fibrous web defining a multiplicity of randomly-spaced small openings extending from a major surface of the web into the interior of the web.
In a second family of embodiments, the invention comprises an absorbent article having a front portion and a rear portion, and a crotch portion between the front portion and the rear portion. The absorbent article comprises, as a first thin-section element, a first layer of thin-section sheet material, a second thin-section element bonded to the first thin-section element and correspondingly attached as an element of the absorbent article by bonds defining a tear-resistant bond pattern, and an absorbent core disposed adjacent one of the first thin-section element and the second thin-section element. The tear-resistant bond pattern has a length, and a width represented by first and second side edges of the bond pattern. The bond pattern reflects application of pressure urging the first and second thin-section elements toward each other in face-to-face relationship to form an array of separate, distinct, and spaced interlocking arcuate bond elements affixing the first and second thin-section elements to each other, in the process of fabricating the absorbent article. The bond elements have spaced first and second ends and corresponding end portions, and arcuate intermediate portions between the first and second end portions. At least portions of the arcuate intermediate portions of selected ones of the bond elements are disposed toward respective side edges of the bond pattern, and the ends of the respective bond elements are disposed inwardly of the side edges.
In some embodiments, the first thin-section element comprises an outer cover, and the second thin-section element comprises a body side liner, and at least one of the outer cover and the body side liner comprises a polymeric material selected from the group consisting of polyolefins, polyesters, and polyamides, and mixtures, copolymers, and blends of such polymeric materials.
In some embodiments, the first thin-section element comprises an outer cover and the outer cover comprises a polymeric film having a composition comprising primarily polyethylene or polypropylene, or a mixture or copolymer comprising polyethylene and polypropylene.
In some embodiments, the second thin-section element comprises a body side liner and the body side liner comprises a material selected from the group comprising porous foams, reticulated foams, apertured polymeric films, polymeric fibers, and natural fibers. The body side liner can comprise a mixture of materials selected from the group consisting of porous foams, reticulated foams, apertured polymeric films, polymeric fibers, and natural fibers.
In preferred embodiments, the absorbent core comprises a matrix of hydrophilic fibers.
In some embodiments of the absorbent article, the length of the bond pattern extends from the front portion of the absorbent article to the rear portion of the absorbent article.
In other embodiments of the absorbent article, the crotch portion of the absorbent article is devoid of the bond pattern.
The absorbent article in the present invention can serve a variety of functions including but not limited to feminine hygiene articles, training pants, diapers, or adult incontinence products.